Building construction



June 13, 1944. R. B. FULLER I BUILDING CONSTRUCTION Filed April 9, 1941 '7 ShetSF-Sheet 1 INVENTOR RwhardBuc/rmmateriizller BY 4 K ATT NEY June 13, 1944.

R, B. FULLER BUILDING CONSTRUCTIO N Filed April 9, 1941 7 Sheets-Sheet 2 June 13, 1944.

R. B. FULLER BUILDING CONSTRUCTION Filed April 9, 1941 7 Sheets-Sheet 3 INVENTOR icImrdBuc/cmirrsferiblier BY Q ia 44.x...)

AT ToR EY June 13, 1944. FULLER BUILDING CONSTRUCTION Filed April 9, 1941 7 Shegs-Sheet 4 INVENTOR RichardBuc/Pminsteriz'rller AT'To NEY Junle 13, 1944. R. B. FULLER 2,351,419

BUILDING CONSTRUCTION Filed April 9, 1941 7 Sheets-Sheet. 5

INVENTOR flick ardfizmfim' insteriz'zller AT'rozNEY 7 Sheets-Sheet 6 R.B.FULLER BUILDING CONSTRUCTION Filed A ri1.9, 1941 June 13, 1944.

INVENTQR Fic/rardBucIrmz'naferiE/Her 44"- '14 I AfT NEY June 13, 1944. R. B. FULLER 2,351,419

v BUILDING CONSTRUCTION Filed Apfil 9, 1941 7 Sheets-Sheet 7 \VIMIIIIIIIIIIIIIM' INVENTOR fiz'clmrdfizlckminsierfilller Patented June 13, 1944 Richard Buckminster Fuller, New York, N. Y.,

asslgnor to The Dymaxion Company, Inc., Wilmington, Del., a corporation of Delaware Application April 9, 1941, Serial No. 387,589

' 3 Claims.

The invention relates to the fabrication of structures suitable for small houses, or for storage bins and the like, and more particularly to structures of this class which have walls of sheet 'metal or other sheet material arranged to form 1 a shell or enclosure which is of substantially cylindrical form. It is an object of my invention to fabricate structures of the class described in such a manher that the walls of sheet metal or other material can be of extremely lightgauge by reason of distribution of stresses throughout the entire structure.

A further object of my invention is to provide a stressed-wall structure in combination with a semi-flexible supporting framework so .as to segregategtensile and compression forces in such a manner that tensile forces are confined substantially entirelyto the wall covering whereas compression forces ,are confined substantially entirely to the supporting framework.

Another object is to make possible the rapid the structure indicated within either of the circles 4 shown on Fig. 1, being a fragmentary elevational view looking at the exterior of the structure, and indicating the manner of draping the outer stressed covering on the framework.

Fig. 7 is a detail elevational view covering that portion of the structure indicated within the circle 1 shown on Fig. 1, and shows the door Jamb and sill; also a portion ofthe flooring.

Fig. '8 is a detail view covering that portion or the'structure indicated within the circle 8 shown on Fig. 1, and shows one manner of applying .the roof sections to the framework.

- Fig. 9 is a perspective view of a portion of the structure illustrated in the preceding views, showing one manner of applying and securing the stressed covering sheets to the framework.

erection of metal structures at low cost for both material and labor.

Another object is to provide a structure of the class described which can be readily taken down and transported to another location for erection here.

Another object is to provide improved means for utilizing the strength characteristics of both the inner and outer wall coverings in structures of the type referred to.

A still further object is to provide means inherent in,- the walls and roof of structures of the class described for controlling or modifying convection currents within the structure.

Other objects and advantages will appear as.

the description proceeds.

In the drawings: w

Fig. l'is a diagrammatic side elevational view of the c pression frame used in a preferred Fig. 10 is a perspective view similar to Fig. 9, but showing another embodimentof the invention in which the means for stressing the cover sheets are so arranged as to leave a doorway free from obstruction;

Figs. 11 and 12 are detail horizontal sectional views of the means for stressing the covering sheets employed in the embodiment illustrated in Fig. 10. Fig. 11 shows the relative position of the parts before the covering has been stressed, and Fig. 12 shows their relative position after the covering hasbeen stressed. I

Fig. 13 is a detail perspective view showing one form of roof construction.

Figs. 14 and l5 are detail transverse vertical sectional views illustrating a modified form of roof construction in which the roof covering sheets are stressed. Fig. lfshows the arrangement of the partsv before the covering sheets embodi' t of my invention; and Fig. 2 is a diagrammatic top plan view of the same frame,

but with the ventilator removed.

. Figs. 3 to a, inclusive. are detail views showing the manner in which the structure of Figs- 1 and 2 is assembled. and-how the outer stressed covering is draped thereon.

Fig. 3 is an exploded view of the joint indicated within the area of circle I on Fig. 1, looking from within the structure. Fig. 4 is a similar view of thejoints indicated within the circles I on Fig. 1, and Fig. 5 is a similar viewof the 'ioin't' lndicatedwithin the circle I on Fig. 1'. v Fig.6 is a detail view covering that portion of providing a more or less flexible supporting frame have been stressed, and Fig. 15 shows the completed roof section. 3

Fig. 16 is a detail elevational view of a modified construction looking from the inside of the strucv ture at the doorway and adjacent panels.

Fig. 1'7 is a detail perspective view looking from the outside of the same structure at a lower corner of the doorway.

Fig. is is a: horizontal sectional view through a portion of the wallstructure'illustrated in Fig.

16. showing the manner of applying the insulation and interior wall covering thereto.

Fig. 19 is a detail horizontal sectional view taken as indicated at lQ-ll in Fig. 16.

- Fig. '20 is adetaiiview showing the manner of attaching the reinforcing. strut members shown lnFig. 16. e

One of the features of my "invention resides in overwhich covering sheets are draped and then stressed under considerable tension. with such a construction the tensile and compression forcesof a plurality of sections arranged and to end.

The ring may be substantially circular or of other generally curved form, or it may be polygonal in form. In the, several embodiments illustrated in the accompanying drawings, a plurality of such rings are arranged in substantial parallelism, and assembled with vertical members to form a caselike structure over which the covering is stretched.

Referring to Figs. 1 to 9, inclusive, I shall describe one of the preferred embodiments which have been selected for the purpose of illustrating certain features of my invention. The construction. shown in these views has been designed primarily for use as a storage unit, such as a "grain .bin or the like. The construction shown,

however, is also applicable to the fabrication of houses, and my invention is not to be understood as being restricted to any particular field of use.

In Figs. 1 and 2, the supporting framework is illustrated diagrammatically, the constructional details of the various portionsof this framework being shown in Figs. 3 to 9, inclusive. In its general arrangement, this framework consists of the polygonal or substantially circular horizontal ring members 8, intersecting vertical members Ill, and inclined radial roof supporting members ii. The roof supporting members H at their inner ends abut a compression ring member |2 (Fig. 2), and at their outer ends are Preferably curved downwardly, terminating in vertical sections II for alignment with the vertical members Ill. The top and bottom ring members 8 are continuous, but the two intermediate ring members 9 may have an open section to provide a doorway or the like, as at A. The top of the doorway. is indicated at it and the sill at IS. A jack l8 may be provided under the end of each vertical member ID for the purpose of leveling the structure. I

The annularrlngs preferably are formed of a plurality of sections arranged end to end with series of straight tubular sections l'l joined together by cross-shaped connecting members It (Figs. 3 and or by studs. I! on the vertical member 10 (Fig. 4). The cross-shaped connect- 8 members I8 also serve to connect the horizontal sections H to the ends of the vertical members l0 and to the vertical portions I! of the roof .members I i. The intermediate Joints 4 may, if desired, be constructed in the same manner as the .struction shown in Fig. 4 the vertical-member l0 is shown as being constructed in a single piece. The cross-shaped connecting members I: have projecting dowels 2B- which fit within the ends of the members III, II and I1, and also within the end of a tubular member 2 I, shown in Fig. 3, which may be driven into the ground to provide a support beneath the column formed by the vertical member Hi. There is one of these supporting members 2| for each of the vertical members It, and the first step in the erection of the structure consists in driving the tubular supporting members 2|. into the ground, preferably with the use of a centering plug placed within the upper end of the member 2|. After the members 2| have been driven so that their top faces are brought to a common level, the elements l1 and i8 of the lowermost ring member 9 are assembled on the foundation thus provided. In a similar manner, the vertical members Ill and the elements of the intermediate and upper ring members-9 are assembled to complete the formation of a lower and upper Joints 3 and i, but in the consubstantially cylindrical or prismatic framework.

The ends of the projections 20 of the cross members ID are rounded, as shown, to facilitate assembly, and also to provide a certain amount of flexibility in the completed structure. If desired, the members III, II and 2| maybe held in assembled relationship with the crosses I8 by any suitable fastening means such as the strap 22 shown in Fig. 3, which has three holes arranged for alignment with tapped holes in the cross member l8, and in the members Ill and 2| (or iii and i3) The cross member l8 may be provided with a flat inner face 23 against which the plate 22 is brought to bear by the machine screw which passes through th center holeof the strap 22.

Machine screws passing through the end holes of the strap 22 engage the tapped holes in the ends of the member I0, and the end-of the member l3 or 2|, as the case may be. The cross members I! preferably are constructed with shoulders 2| so as to bring the body portion of the member I. into flush alignment with the,outer surfaces of themembers||I,||,||and2|.

The studs I9 shown in Fig. 4 may be welded or otherwise secured to the vertical tubular member i0 and preferably are tapered similar to the studs 20 of the cross members |8.so as to provide a certain amount of flexibility in the completed structure, and also to assist in its assembly. The studs l9 likewise are formed with shoulders 25 so that the attaching portions of these studs come into flush alignment with the outer surfaces of the sections l'l.

The connection between the roof members II and the compression ring i2 is illustrated in Fig.8.

The ring I2 is provided with studs'26 similar in construction to the studs I8 which have been described with reference to Fig. 4. These studs may bewelded or otherwise secured to the ring l2. The inner ends of the tubular roof members fit around the ends of these studs, and are forced against the shoulders 21 thereof when the outer wall covering is stretched over the cylindrical walls of the frame. The ring |2 in conjunction with the roof members thus serve to true up the completed structure. I

After'the supporting foundation members 2| have been driven and leveled, a band or strip 28 of metal or other suitable material is wrapped, around the outside of the members 2| as shown in Fig. 3. This may be done after the rest of the framework has been assembled. With the strip 28 in place, the foundation of the structure is v accrue sued to the desired level, as indicated at 2:. The

na 20 may be of earth, or of any other material desired. Then, after the framework has been assembled in the manner previously described, the wall covering sheets 30 and ii are draped on the structure. For this purpose, the vertical members II are provided with outwardly projecting studs 32 (Fig. 8) for/engagement with slots at termed in the sheets ll and". The engagement of the slots in the-sheets with the studs 32 serves to'support the sheets in the proper position during their application, while allowing relative movement between the sheets and the vertical members ll during the. operation of stressing the covering sheets. The ends of the sheet members are secured to vertical members such as the channels 34 (Figs. '7 and 9), as by welding or bolting the sheets thereto. The channel 34 hooks over one of the vertical members It, holding one end of the sheet as it is wrapped around the structure to'have its opposite end secured to another channel )4 at the adjacent vertical member l0. Application of the covering sheets 30 and 3i may be facilitated by having the sheets delivered in roll form and, if desired, the .slots 33 may be punched priorto application of the sheet. The

The roof covering may consist of. a plurality of segments 4| having curved flanges 42 adapted to extend over the roof supporting members I I. The

roof segments 4| are provided with downwardly extending flanges at their outer ends arranged to overlap the top; of the wall as at 43. At their inneredges, the roof segments are'provided with flialngleg 44 adapted to extend over the compression r g In Fig. '7 I have shown an illustrative section o'fcorrugated flooring 45. Asphalt mastic 48 or other suitable material may be used to seal the Joints between the flooring and the ring sections I1 and between the ring sections l1 and the covering sheet 30.

In Fig. 10 I have shown a modified form of my invention which is particularly suited for the construction of houses, where an opening for a full height door must be left free from obstruction by turnbuckles or the like. The construction of this embodiment is the same as that which has been described insofar as concerns the ar rolled sheet may be mounted on a spindle carried by a hand truck 88 on which it is rotatably mounted. As the truck is pushed or pulled around the structure, the sheet unrolls and the slots 33 brought into proper registration with the studs 32 in the framework. The lower sheet 30 is applied first, and the upper sheet 3| overlaps the lower sheet, as at 31, to provide proper protection against the weather.

' draped on the structure, the vertical members 34 are drawn towards one another by means of turnbuckle rods 38, the ends oi which are suitably secured to the channels 34. As will be seen in Fig. 9, the sections ll of the uppermost and lowermost compression rings 8 extend across the opening between the ends of the covering sheets. The back and one flange of the channels 34 are cut away so as to avoid interference with these sections ll. As the turnbuckle rods 38 are tightened to draw the channels 34 toward one another, the rings are placed under compression, holding the sections ii and i8 thereof in "assembled relationship. The vertical members I 0 adjacent the channels 34 are prevented from being drawn toward one another by reason of the fact that the uppermost and lowermost compression rings are continuous. Therefore, as the channel members it are drawn tdward one another, the vertical members it, which are surrounded by the flanges of these channel members (Fig. 7) are held apart by the sections ll of the compression rings which extend across the same space that is occupied by the turnbuckle rods. Since the pull applied by the turnbuckle rods is not directly in line with the plane of the covering sheets, a turning moment is applied to the channels 34 in a direction about an axis which parallels the length thereof. This turning moment is resisted by a second set of turnbuckle rods 39 which are to the vertical member in at the end of th adiacent panel, and at their other ends to studs 49 (Figs. 7 and 9) rigidly secured to one side of the channel 84. It will be seen that by properly adlusting the turnbuckles 38 and I8, proper alignment-oi the channels 84 may be secured.

' nel members 36. The action of the jacks 41 in secured at one end rangement of the supporting framework. and the wall covering sheets 30 and 3|. Also, the ends of the wall covering sheets are attached to channels 34 in the manner which has been'described with reierenceto Fig. 9. However, in place of the turnbuckle rods 38 I employ a series of Jacks 41 arranged in the panel adJacent the doorway. As shown, there is a set of these Jacks 41 at each side of the doorwayso that the take-up instretching the covering sheets may be distributed evenly around the structure. However, if desired, the Jacks may be omitted at one side of the doorway, in which case the channel 34 at that side will simply be drawn up tightly against the vertical member l0 so that all of the stretch may be taken up at the other side. The two intermediate jacks s1 bear at one end against the vertical members It at the studs l9, and at the other end bear against the flanges of the channel 34. The lowermost and uppermostjacks 41 are arranged adjacent the compressionring sections ll. Thus, Just as has been described with reference to the embodiment of Fig, 9, the uppermost and lowermost horizontal compressionrings tare continuous, i. e., they extend completely around the structure and prevent it from collapsing when the sheets are stretched thereover by means of the Jacks 41. Turnbuckle rods 39 attached at one end to one of the ver tical members it, and at the other end to a stud 4s on the channel 34, cooperate with the Jacks window openings 48 may be preformed in the covering sheet 3 l It will be understood that the tensioning of the covering sheets is accomplished with very little relative movement between the two chantightening the covering sheet 30 is illustrated in Figs. 11 and 12, Fig. 11 showing the relative position oi the parts before tightening; and Fig. 12 their relative position after tightening. The jack 41 is recessed atone end to receive the dowel i9 secured to the vertical member Hi. If desired, the base of the jack may be made arcuate in form, as 'at 49, for engagement with the vertical member liito prevent rotation of the base portion of the Jack during its operation. The

head 50 of the jack is keyed to the screw it thereof,.as.by means of the pin 52, and is provided with a recess 53 arranged to surround the erating the Jack. As the Jacks are operated to draw the sheets 30 and ii taut over the frame, the channel 34 moves to the rightas indicated by the arrow a in Fig. 12, but the position of the adjacent vertical member HI remains substantially unchanged for it is held by the continuous compression rings at the top and bottom of the structure. As the channel 34 moves to the right as indicated in Fig. 12, its lower end slides over the top of the sill 55 without interference therewith.

The connection for the inner end of the turnbuckle rod 3! is shown in Fig. 12, and may comprise a shackle 58 secured to the vertical member III by means of a bolt 51, the end of the turnbuckle rod being received between the biiurca: tions of the shackle 56 and secured thereto by a pin and cotter 58.

Fig. 13 shows a detail of the construction or the roof for a grain bin or the like to provide an opening for loading and. unloading or other purposes. The constructionof the supporting framework may be the same as has been described with reference to Figs. '1 to 9, and as shown, comprises the tubular roof-supporting members H which extend radially oi the structure, and the compression ring ii to which the inner ends or the members II are secured. Each root panel 4| spans the distance between two of the members H', and is provided with marginal flanges 42 arranged for engagement with the members H or with the flanges oi adjacent panels. The

flanges is, preferably are curved or bent over in such a manner as to provide an interlocking engagement between the flanges of adjacent panels. and an interlocking engagement with the members II as indicated at b in Fig. 13. The flanges 42 of the central panel 4| shown in Fig. 13 overlie the flanges of the adjacent panels so downwardly extending flanges .2 bearing against the overlapping edges of the sheets at each side 01 the supporting member H. A series or clamping bolts 63 extend through the memb'er ll, through the overlapping. portions or the sheets 60, and the center of the clamping element I.

When the clamping bolts '3 are tightened, the

overlapping portions of the sheets 8| are drawn down around the member I I, as indicated in Fig.

15. This action stresses the covering sheets because of the material taken up by wrapping the marginal edges of the sheets around the surface of the member II. It desired, the bolts 63 which are nearest the center of the structure, may be tightened to a lesser extent than bolts which are toward the outside, so as to properly distribute the stress throughout the roof. Also, the tightening of the bolts I may be performed in such a manner as to regulate the clamping action or the elements I to, stress the root to approximately the same tension as the wall covering.

The resulting even distribution of stresses throughout the entire structure makes it possible to employ lighter sections than would otherwise bepossible.

In Figs. 16 to 20, inclusive, I have illustrated another embodiment of my invention which is more particularly adapted to the construction of houses'or other structures in which it is desirceding views, consisting of vertical walls members ll, horizontal compression rings made up of tul'ailar sections l1, and roof members il. However, only one intermediate compression ring is employed in place of the two rings 0 shown in Fig. 1. In this connection, I wish to make it clear that the number of intermediate rings is purely a matter of choice, and that, in the emas to permit the central panel to be raised in the the central panel in only partially'elevated position audit will be understood that it may be swung upwardly to the extent which may be desired for loading operations. The panel II which completes the wall enclosure between the ends oi the wall covering sheets II and ll likewise may be removed to facilitate loading or imloading or the bin. .11 desired,'the panel ll may be connected to thedownwardly extending portion 43- "or the central roofpanel so that when'this panel israised, the section I! will be raised with,'it.--

v In Figs. 14 and 15 I have illustrated a modified form of root construction to provide for stressingot the roof covering sheets. These are cross-lectional views taken transversely or oneoi the root panels. The construction oiFJhe' supportingi'ramework may be similar tothat which has been described comprising the tubular supporting members II. 'In this embodiment of the invenbodiment about to be described, one or more intermediate rings may be employed, as may be desired. The intermediate compression ring (or rings) does not extend completely around the structure because of the necessity of providing a full height door ning. The top and bottom compression rings do extend completely around the structure. Howeve at the doorways jack 'l takes the place of once! the sections ll. Oompression forces which are set up in the supporting framework upon stressing of the covering v sheets are transmitted from the upper and lower conveniently be secured attheirends v cross-shaped connectingmembers I. and

ll previously described members "and I, maybe tapped-to receivecyebolts II (Fig. 20) for engagement with eye-bolts ll formed in the ends or the rods.

tion, the covering sheets I. may be flat sheets devoid of marginal flanges, as indicated in Fig. 14. AdJacent edges or the sheets I are arranged in overlapping relationship above the supporting members ll. A clamping element or batten 6 l is placed above the overlapping portions of the sheets. The clamping element may be in the form of a channel in cross section so as to provide 0f the struts M makes it compressive strengtho! the discontinuous intermediate compression ring.

The wall coveringmheets II, II arefapplied in the manner which has been described with reference to Fig. 9. In-thls embodiment the ends 01' the sheets II, II ar welded or otherwise secured to angleemembers ll. Eye-bolts" are secured to the corners oi the angle members 01 in line with the planeo't the covering sheets, and turnbuckle rods "adjacent the Jacks 41 at the top and bottom of the doorway are to the'eye-bolts just described, stressing 30 and 3| may be accomplished by tightening the turnbuckle rods 38, or

by extending the jacks 41, or by conjoint manipulationoi' the jacks and tumbuckles. This makes it possible to obtain the desired stress in the covering while at the same time avoiding interference between the angle members 81 and the door frame. If, as the rods 38 are tightened, the members 81 come up against the door frame, the jacks 41 may be operated to complete the stressing operations; or, if desired, the tumbuckles SI and Jacks 41 may be so regulated as to bring the members 81 tightly against the door frame 69 just as the desired stress has been secured, thus providing a tight seal between the wall and door frame. Again, the jacks and tumbuckles may be so adjusted as to leave just a small clearance between the members 81 and door frame suflicient to permit the introduction of the desired quantity of mastic sealing compound therebetween. It will be seen that with the construction described, operation of the Jacks "serves to enlarge the entire supporting framework slightly so as to stress the covering sheets, whereas operation of the turnbuckle rods 38 likewise serves to stress the covering sheets, but by direct action.

My invention also contemplates the stressing of the interior wall covering so as to utilize its strength characteristics in the finished structure. This feature is illustrated in Figs. 16, 18 and 19 which show an interior wall sheet ll provided with grommeted apertures 12 at intervals which may be spaced in conformity with the spacing of the intersections between the frame members it and I1. Bolts I3 or other suitable clamping means pass through the grommets I2 and through apertures in the cross members 18 or vertical members It. In the Joint shown in Fig. 19, the bolt 13 also passes through the plate 22, which was described with reference to Fig. 3. When the bolts 13 are tightened, the wall sheet H is drawn outwardly .toward the framework of the structure so as to place this sheet under tension and impose additional compressive forces on the frame.

Before the interior wall covering H is applied, insulating batts it may be placed against the outer wall covering between the uprights it as shown in Fig. 18. In some cases it may be preferred to fill the space between the inner and outer wall coverings with insulation in loose form after both coverings are in place.

When the structure is to be employed as a tool supply house, store, or for other purposes, it may be desired to arrange shelving around the inside, and for this purpose, the vertical members in maybe provided with slots 15 (Fig. 16) for engagement by projections on the shelf supports.

In its preferred form, my invention contemplates the application to the finished structure of coatings of different heat absorptive capacities. For example, in the case of a grainbin or other storage unit where it is desired to reduce the magnitude of convection currents within the structure notwithstanding the provision of a ventilator at the apex of the roof, I paint the roof with a light-colored paint such as aluminum or white, and the side walls with a dark paint which ably, a plurality of coatings are used such that the color becomes gradually darker toward the bottom of the bin to create a low temperature gradient within the structure dependent upon the differential in heat absorptiveness of the pigment used in the coating. The diminished temperature gradient within the bin results in a more nearly static air condition while at the same time permitting proper ventilation.

'In a structure used for houses, the roof will ordinarily be provided with a dark, heat absorptive, coating. and the walls will be made progressively lighterin color so as to be more heat reflective or heat insulating at the bottom. This will create convection currents moving upwardly along the interior walls and ceiling to the ventilator, while cool fresh air will be drawn in around the bottom. Depending upon climatic conditions, it may be desired, however, to utilize in a house the same means as has been described above in connection with storage bins and the like, viz. to provide a structure with roof and walls of heat absorptivity which increases toward the bottom of the structure.

I also contemplate the use of interior coated surfaces having a diflerentialheat emissivity such that the interior heating eflect of radiant every case, the coating or'coatlngs are such as to create a differential in the interior heating eifect of radiant heat reaching the outer surfaces or the, structure, as by direct sunlight or infra red rays, such that this heating 'efl'ect varies from the top to the bottom of the structure whereby convection currents within are modified accordingly.

It will be understood that the features which I have described in bodiments of my others of the embodiments. For example, the

connection with certain emvmanner of attaching the turnbuckle rods 38 to the ends of the covering sheets, as described with Figs. 16 and 17, may be employed in con- Junction with the other-structure illustrated in Fig. 9, in which case the turnbuckle rods 39 can be eliminated because there willbe no turning moment-on the channels 31. The terms and expressions which I have employed are used in a descriptive and not a limiting sense, and I have no intention of excluding such equivalents of the invention described, or ofportions thereof, as fall within the purview of the claims.

1. A structural unit of the class described comprising a frame-work of compression members arranged to form a support for a continuous either alone, or in invention may be applied to members attached to said sheet for adiustably increasing the distance between said vertically arranged section and said vertical member to tighten said sheet member over said frame-work.

2. A structural unit of the class described which comprises a frame-work arranged to form a support for a substantially vertical continuous wall, said frame-work comprising horizontal ringlike members and vertical members, a sheet member wrapped around the periphery of said framework, vertical members secured to the ends of, said sheet member, screw means for applying a I force to at least one of said vertical members secured to the ends of said sheet to bring the sheet ends toward one another, and a brace extending from each of said last-named vertical members to a fixed part of said frame-work to counterbalance the turning moment applied to said vertical members by said screw means.

3. A structural unit of the class described comone another to draw said sheet member tightly over said framework, said means comprising a tension element engaging said vertical members and extending across the opening between said pair of adjacent vertically arranged sections. and

said means also comprising a'compression elev ment disposed between said pair 01' vertically arranged sections.

RICHARD BUCKMINSTER FULLER. 

